Strap stretching device



Oct. 2, 1951 J. N. WOGNUM STRAP STRETCHING DEVICE 2 Sheets-Sheet 1 Filed Feb. 4, 1948 -lTllinni -il L JNVENTOR. @mes/l/ BY Oct. 2, 1951 J. N. WOGNUM STRAP STRETCHING DEVICE 2 Sheets-Sheet 2 Filed Feb. 4, 1948 ]N V EN TOR. /fzmeallflggmm,

Patented Oct. 2, 1951 STRAP S'TRETCHING DEVICE James N. Wognum, Chicago, Ill., assignor to Acme Steel Company, Chicago, 111., a corporation of Illinois Application February 4, 1948, Serial No. 6,261

1 20 Claims.

This invention relates to improvements in a strap stretching device adapted for used in drawing taut, around a box Or package, metal strap or binder, preliminary to securing the ends of the strap or binder together.

Many features of the present invention may be employed with particular advantage when embodied in a strap stretchin device of the socalled pusher bar type in which one end of the strap is held in fixed relation to the stretching toolby abutting the end of the tool against a metal seal attached to the strap, for example, by threading the strap through a tubular seal and reversely bending the end of the strap, and the strap is then drawn taut by drawing the supply end portion through the seal through the operation of the stretching mechanism. One form of such a device is disclosed in the United States Letters Patent of Frederick A. Endress, No. 2,232,376, dated February 18, 1941.

In the use of prior tools of that type it has been customary to draw out the required length of strap for a particular strapping operation with one hand, while restraining the supply portion with the other hand, and then to thread the strap into the gripping devices of the tool after it has been threaded through a tubular seal and looped around a package. This operation is liable to cut the hand of the operator, particularly when the strap is of very thin gauge and it has the further disadvantage that the strap has to be threaded into the tool on each strapping operation.

In many strap stretching tools, the strap gripping devices are of a type which require the insertion of the strap laterally and these devices are supported only at their inner ends so that the strains set up by the stretching operation tend to spread the outer portions of the gripping devices and thereby cause them to release the outer portions of the strap.

When the strap is gripped by a rotary member which also effects the stretching, it has been customary to employ a circular member havin a transversely serrated peripheral surface for engaging the strap and also a separate relatively fixed ratchet wheel having teeth of substantial size controlled by a pawl and detent for rotating the gripping wheel and taking up and holding successively increments of the strap or binder until the strap has been drawn taut. This arrangement has the disadvantage that fine increments of adjustment of the size of the final loop of strap are not possible. When the object to be bound is substantially incompressible, such as a tit bundle of steel rods or tubes, it frequently happens that the holding detent is riding upon the inclined portion of a ratchet tooth when the most desirable degree of tension has been set up in the strap. The application of further tension to cause the detent to engage the shoulder of the tooth would break the strap while a release of the tension to cause the detent to engage the shoulder of the precedin tooth would cause the strap to be loose on the bundle. On the other hand, when the package is compressible, it may be damaged by overtensioning the strap in the efiort to cause the detent to engage a desired tooth.

One object of the present invention is to overcome the danger of injury to the operators hand and to insure greater convenience in operation by providing a strap stretching tool having a guide or channel through which the strap is withdrawn from the source of supply while held in the operators hand. A further object is to provide a strap stretching tool in which the leading end of the strap is always retained after each strapping operation so that it is not necessary to thread the strap into the tool until after an entire coil of strapping has been consumed. Another object of the invention is to provide a strap gripping device, capable of use with tools of various types, which is supported at both its inner and its outer ends, whereby a uniform grip is maintained upon the strap throughout its width. Still another object of the invention is to provide a strap stretching tool having strap gripping and stretching means of the rotary type wherein a single finely toothed wheel serves as a strap gripping and feeding device and also as a ratchet wheel, thus simplifying the construction and making it possible to obtain fine increments of adjustment of the tension of a strap so that it will have the proper relation to the encircled box or package. proved means for mounting the rotary gripping device and for efiecting its release from the strap. Another object of the invention is to provide a simple strap stretching device composed of few parts, many of them metal stampings, which may be economically manufactured. Other objects rclate to various features of construction and ar rangement which will appear more fully herein after.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which one embodiment is illustrated.

A further object is to'provide im- In the drawings,

Figure 1 shows an end elevation of the bale or package having a binding strap passed around it and having the strap stretching device of the present invention in operative relationship to the strap;

Fig. 2 shows the use of the strap stretching de vice of the present invention in drawing taut a binding strap around a group or bundle of steel tubes or the like;

Fig. 3 shows an enlarged side elevation of the strap stretching device of the present invention with the strap stretching and gripping wheel in its operative position;

Fig. 4 shows a top plan view of the strap stretching device illustrated in Fig. 3;

Fig. 5 shows an end elevation of the improved strap stretching device, looking toward the right as viewed in Figs. 3 and 4;

Fig. 6 shows a bottom plan view of the improved strap stretching device shownin Figs. 3 and 4;

Fig. '7 shows a vertical sectional view taken on the line 1-1 of Fig. 3;

Fig. 8 shows a longitudinal section and partial side elevationv on the line 8-8.- of Fig. 4, illustrating the use of the device in drawing a strap taut; and

Fig. 9 shows. a side elevation of the strap stretching device when the strap gripping and feeding wheel has been elevated from its operative. position to permit the threading of a strap into the device.

Asqillustrated in Fig. 1 of the drawings, the improved strap stretching device It is shown in use in applying a metal strap II around a bale or. package I2. The end of the tool abuts against a tubular metal seal I3 which is attached to the leading end of the strap and. the supply portion I Id of the strap, leading from a. supply coil or the like, is drawn through the guideway of the tool by the operation of the stretching mechanism.

The use of the strap stretching tool II] in stretching a metal strap I4 about a bundle of steel tubes or the like I5, is shown in Fig. 2 where the strap is shown as having been operated upon by the tool It! to the point where it is stretched, i. e., drawn taut, around the bundle of tubes preliminary to deforming the seal I6 and the enclosed strap portion to form an interlocking joint. It is in connection with the binding of this type of bundle that a precise degree-of tensionin the strap is important in order that the strap may be drawn taut without exceeding the elastic limit of the metal.

As illustrated more particularly in Figs. 3 to 9,

inclusive, the improved strap stretching tool comprises a frame or bar I8 which is generally of channel shaped form, being open upon its upper side. At its forward end, this frame is provided with a tip portion IBa'having upper and lower walls which converge toward the extremity of the bar, the top wall being formed by flanges IBb which are spaced apart to form a narrow slot I 80, shown in Fig. 4. The walls of the tip portion form a mouth which is slightly wider than the width of the strap and slightly greater in its vertical dimension than the thickness or gauge of the strap. At the rear of the tip portion I8a, the frame or bar I8 is provided with upwardly extending parallel side flanges Mid and, to the rear of these side flanges, the bar or frame is formed. of upstandingside walls which are turned inwardly to form top flanges having their edges spaced apart as shown in Fig. 4. There is thus formed a guide channel I9 through which the 4 metal strap II is passed endwise from the source of supply.

In the use of the tool, the supply portion I la of the strap, drawn from a coil or other source of supply, is threaded through the channel I9 of the bar or frame I8, through the tip portion I8a thereof and thence through the tubular seal I3, after which a loop of the strap II is formed around the box or package to be bound and the extremity I II) of the strap is then threaded again through the tubular seal I3 beneath the supply portion Ila. of the strap. The extremity IIc of the strap is then reversely bent beneath the seal, as shown in Fig. 8, to form a connection between the seal andthe end of the strap which is maintained by the pressure of the seal and strap against the box or package during the binding operation. The extremity of the tip portion I8a of the'bar or frame is then caused to abut against one end of the seal I3 as shown in Figs. 1 and 8, whereupon the supply portion Ila of the strap ismoved toward the right, as viewed in Figs. 1 and 8, by the operation of the stretching mechanism hereinafter described, thereby drawing the strap taut around the bundle or package.

The side flanges I8d of the bar or frame I8 are provided with enlarged apertures I8f', shown particularly in Figs. 8 and 9, which'are loosely engaged by a pin or shaft 20 having-its extremi' ties journaled in the side arms 21a of a yoke= shaped bracket 2I which straddles theun'derside of the member I 8 with its arms 2 Ia'extendingunwardly inparallel relationshipto the flanges Ifld, as shown particularly in Figs. 4, 5, 6 and '1. The pin 26 is. retained in place by U-shaped spring clips 2 which engage annular. grooves 2Il'a'f'ormed in the ends of the pin outside of the arms 2111. This pin or shaft 20- has journaled thereon. between the side flanges I'8b ofthe bar or. frame. a circular strap gripping and. feeding wheel-22 provided. around. its periphery with aplurality. of very fine and uniformly spaced teeth or serrations 22a. which. are. adapted to coactwith the upper surface of a strap seated onthe bottom of the channel I9 and also to cooperatewiththe pawl and detentmechanismhereinafterdescribed in the strap stretching operation.

The toothed wheel 22 is-normally maintained inproximity to, but out of engagement with, the top surface of the channel I9 or in contact-with the strap if there is a strap seated in thatchannel, by a leaf spring 23 which is secured to-the cross member 2 lb. of the yoke-shaped bracket-2 I, as shown-in Figs. 3, 8 and. 9-. The member 21 has a tongue 2Ic which extends forwardly-and upwardly beneath the tip portion of a flange I.8g which is punched cutof the bottomwall. of channel I9 as illustrated particularly in Figs. 6-.and.8. Theleaf spring 23 extends rearwardly from the yoke-shaped member 2| and has. its tip. seated above another tooth I871 which is punched. out of the bottom wall of the channel I9- The down.- ward movement of the wheel 22 is limited by the engagement of the pin 20 with the bottom walls of the apertures I8), thus holding. the teeth 220 out of contact with the bottom wall of the channel I9 when there is no. strap in the. channel. This spring tends normally to. move the. cross bar 2.I b. of thebracket 2I upwardly with a corresponding downwardly tilting movement of. the forward portions of the arm 2Ia in which the pin or shaft 20 is journalled, thus carrying the strap gripping and feeding wheel 22 downwardly tgward the strap which is seated in. the channel I The rotation'of thegripping and feeding wheel 22' is effected by a reciprocating lever .25which is provided at its 'forward end with parallel .side flanges 25a extending on .opposite sides .of the wheel .22 and between this wheel and the side flanges 18d .of the bar or frame '18, :as. shown particularly in'FigJ. 7.. These side flanges 2.5a are provided with apertures in which. the pin or shaft 2l1is 'journalled and thelever.25-.may, there- Lfore, be swung in a vertical plane abouttheshaft 20 during the operation of efiecting rotation of the wheel '22..

Inorderto make the reciprocation .of thelever 2.5 .efiective in rotating: the toothed wheel 22 in the direction of the arrow .21, :the lever is .provided with. a pawl :28. "which isrin" the :form of .a substantially fiat bar having its end portions seated in triangularzshaped apertures25b which are. formed in the side flanges 25a of the lever. The .pawl '28 is rounded at its lower end for engagement "with the rounded lower corners. of the aperture .2.5b,.;and-:the upper edge-of the pawl is provided with a right-angular corner which is adapted to cooperate with the teeth of the wheel 22 in effecting rotation of the wheel when the leveris moved. upwardly from the position shown in Figs. 3,. 8 and 9... This. pawl :28 is normally maintained in engagementywith the teeth of the wheel 22. :by means of a wire. spring .29, shown particularly in Figs. 4,..8 land 9, which is somewhat :u-shaped: in iorm with they curved upper extremity 22a thereof bent transversely and hooked over the-upper edge of the top flange 250 of thejlever. Thearms 2-.9bpf this springextend downwardly :and beneath the lower edge of the pawl 28 .andxare thence ecarried upwardly on the forward side of the pawl and extended through apertures 2.8a which areformed in'the .pawl; the extremities 12.90 of the :springbeing bent upwardly on the rear side of the pawl so that the normal tendency of the spring 29 is to rock the pawl about its lower edge and .toward the toothed peripheral-surface of the wheel 22. After anupward movement .of the lever 25 withacorresponding angular movement .of the wheel 22., ,a. reverse movemento-f the lever toward its lower position will cause the pawl .28 to slide over the teeth of the wheel 22 in the usual fashion.

-.After each increment of rotation of the. wheel 22 by an upward and forward movement of the lever 25., which. is. provided .at its. end with a rounded handle25 adapted for convenient engagement by the operator, the. wheel is held in its advanced position .by means of a :detent 30 which is in the form of a flat bar similar to .the pawl .29 and which 'has its. ends mounted for pivotal movement in triangular shaped apertures vli8i which are formed in the side flanges .lBd of the barof frame 18. This detent 30 has a rounded upper edgewhich :is. adapted to rock in the rounded upper extremities of. the apertures I82 and its lower edgeis of angular form adapted to cooperate with the teeth of the wheel 22 to prevent reverse .rotation of this wheel after it has been released by the pawl 28. The detent 3,0 is normally-moved .into engagement with the teeth 22a by means of a wire spring .31 which is of yoke-shaped form with the yoke portion 3| a thereof seated. beneath the top flanges 18b of the tip portion. of the bar or frame 18,. as shown particularly in Figs. 4, .8 and .9. Theside arms 3H) of this spring extend rearwardly and overthe top rounded edge of the detent 30 from which point these arms are bent downwardly and then through apertures 30a which are "formed in the detent, the extremities of the arms-o1 the spring beingdirected downwardly on the underside of the .detent. so that the normal action of the spring 3| is to force the lower edge of the detent inwardly into engagement with the teeth 22a, of the wheel so that the wheel is held against rotation between successive operations of the lever 25.

When it is desired to thread a strap through the channel I9 and the tip portion |8a of the bar or frame 18, the toothed wheel 22 is elevated from the bottom of the channel in the bar or frame by pressing downwardl on the lever 25 after it has reached the position shown in Fig. 8, thereby causing the lever to rock on the downwardly extending shoulders 25c which are formed on the side flanges thereof to engage the upper surfaces of the bar or frame at opposite sides of the slot Hie. When the lever 25 is rocked on these rounded shoulders 25e, the bracket .21 is tilled and the .toothed wheel 22 and the shaft 20 are elevated against the action of the spring '23,

thus carrying the toothed wheel 22 upwardly from the position shown in Fig. 8 to that illustrated in Fig. 9, thereby providing a space beneath the toothed wheel through which the strap may be readily threaded. This spaced relation of the teeth of the wheel 22 and the bottom of the channel in the bar or frame l8 may be varied by the tilting of the bracket .21 against the aciion of the spring 2.3 in order to accommodate straps of diirerent gauges.

After the strap has once been threaded through thebar or frame [8, it remains in the tool, being held by the spring pressed gripping and feeding wheel 22, until all the coil or other supply of strapping has been consumed, whereupon the leading end of the strap ofanother coil ispushed through the guide channel l9 and the tipportion 1.8a after rocking the wheel 22 upwardly to the retracted positionshown in Fig. 9.

During the operation of drawing a strap taut around a box, package or bundlemrother object, the strap is moved toward the right through the guide channel of the tool by successive operations of the lever 25,. while the free end of the strap is held stationary by the engagement of the seal I3 with the end of the tip portion Ma. The teeth 2.2a ma be made very fine in order to obtain a better grip on the strap and in order to permit Very fine increments of adjustment of the tension in the strap. For example, the apices of the teeth 22a may-be 3% of an inch or less apart. These teeth are preferably formed so thatthe ope posite sides of each tooth are of equal depth and of the same inclination to a radius of the wheel passing through the apex of the tooth. Because of this possibility of obtaining very fine degrees of adjustment in the tension of the strap, it is possible to obtain a precise degree of iautness in the strap which is suitable for the character of the object being bound.

The primary parts of this strap stretching tool, namely, the member l'8, the lever 25 and the yoke-shaped member 2| may preferably be formed as steel stampings, thus simplifying the manufacture of the device and greatly reducing its cost as compared with other forms of strap stretching devices heretofore used.

Although one form of the invention has been shown and described by way of illustration, it will be understood that it maybe constructed in various otherembodiments which come within thescope of the appended claims.

I claim:

1. In a strap stretching device, a bar having a guide channel adapted to receive and laterally confine a strap, means for gripping said strap in said channel, and means for operating said gripping means to move the strap in said channel.

2. In a strap stretching device, a bar having a channel adapted to receive and laterally confine a strap thrust into the channel endwise, and

a gripping member mounted to engage and hold the strap in said channel.

3. In a strap stretching device, a bar having a channel adapted to receive and laterally confine a strap thrust into the channel endwise, a gripping member mounted to engage and hold the strap in said channel, and means for operating said member to effect movement of said strap endwise through said channel.

4. In a strap stretching device, a frame member having means for supporting a strap, a gripping Wheel having peripheral teeth adapted to engage and hold said strap, and means having parts engageable with said teeth for effecting rotation of said wheel and thereby causing endwise movement of said strap.

5. In a strap stretching device, a frame member having means for supporting a strap, a gripping wheel having peripheral teeth adapted to engage said strap, means including a spring for causing said wheel to grip said strap, and means engageable with said teeth for rotating said wheel and thereby efiecting movement of said strap.

6. In a strap stretching device, a frame member having means for supporting a strap, a gripping wheel having peripheral teeth adapted to engage said strap, means including a spring for causing said wheel to grip said strap, and means including a reciprocating lever and a pawl and detent engageable with said teeth for effecting rotation of said wheel and endwise movement of said strap.

7. In a strap stretching device, a frame member having a guide channel through which a strap may be moved endwise, a gripping member engageable with a strap in said channel, means for actuating said gripping member to effect endwise movement of said strap, and a mount for said gripping member, said mount being actuated by a part of said actuating means I for moving said gripping member away from said strap.

8. In a strap stretching device, a frame memher having a guide channel through which a strap may be moved endwise, a gripping mem-.

ber engageable with a strap in said channel, means including a spring for moving said gripping member into engagement with said strap, means for actuating said gripping member to effect endwise movement of said strap, and means actuated by a part of said last named means for moving said gripping member away from said strap.

9. In a strap stretchin device, a frame member having a guide channel through which a strap may be moved endwise, a gripping member, a bracket resiliently mounted on said frame member, a pivot pin carried by said bracket for supporting said gripping member, and means mounted on said pivot pin for actuating said gripping member to effect endwise movement of said strap.

10. In a strap stretching device, a frame member having a guide channel through which a strap may be moved endwise, a gripping member, a bracket, 9. pin mounted in said bracket and having said gripping member mounted for rotatable movement thereon, means for resiliently mounting said bracket on said frame member to cause said gripping member to engage said strap in said channel, and means for actuating said gripping member to effect endwise movement of said strap.

11. In a strap stretching device, a frame member having a guide for a strap, a gripping wheel having peripheral teeth adapted to engage said strap, a pin on which said wheel is rotatably mounted, a bracket for supporting said pin at both ends, and means for resiliently mounting said bracket on said frame member and causing said teeth normally to engage said strap.

12. In a strap stretching device, a frame member having a guide for a strap, a gripping wheel having peripheral teeth adapted to engage said strap, a pin on which said wheel is rotatably mounted, a bracket extending under the strap for supporting said pin, means for resiliently mounting said bracket on said frame member and causing said teeth normally to engage said strap, means including a reciprocatory lever for rotating said wheel and thereby effecting endwise movement of said strap, and means actuated by an abnormal movement of said lever for moving said wheel out of engagement with said strap.

13. In a strap stretching device, a frame member having a guide for a strap, a gripping wheel having peripheral teeth adapted to engage said strap, a pin on which said wheel is rotatably mounted, a bracket for supporting said pin, means for resiliently mounting said bracket on said frame member and causing said teeth normally to engage said strap, and means including a reciprocatory lever and a pawl engaging said teeth for rotating said wheel and thereby effecting endwise movement of said strap.

14. In a strap stretching device, a frame member having a guide for a strap, a bracket mounted on said frame, a gripping member carried by said bracket, a spring attached to said bracket and engaging said frame to cause said gripping member to move normally into engagement with a strap in said guide, and means including a lever pivotally supported by said bracket for actuating said gripping member to effect endwise movement of said strap in said guide.

15. In a strap stretching device, a frame member having a guide for a strap, a bracket mounted'on said frame, a gripping member carried by said bracket, a spring attached to said bracket and engaging said frame to cause said gripping member to move normally into engagement with a strap in said guide, and means including a lever pivotally supported by said bracket for actuating said gripping member to effect endwise movement of said strap in said guide, said lever having a projection adapted to engage said frame upon abnormal movement of said lever to move said bracket with respect to said frame and thereby move said gripping member away from said strap.

16. In a strap stretching device, a frame having a guide channel through which a strap is adapted to pass endwise, a yoke-shaped bracket embracing said frame and having arms extending upwardly on the outer side of said frame, said frame having side flanges located inside of said arms and provided with apertures, a pin mounted in said arms and loosely engaging said apertures, a gripping member mounted on said pin between said flanges, and resilient means engaging said frame and said bracket for causing said gripping member normally to engage a strap in said guideway.

17. In a strap strecthing device, a frame having a guide channel through which a strap is adapted to pass endwise, a yoke-shaped bracket embracing said frame and having arms extending upwardly on the outer side of said frame, said frame having side flanges located inside of said arms and provided with apertures, a pin mounted in said arms and loosely engaging said apertures, a gripping member mounted on said pin between said flanges, and a spring fixed to said bracket and engaging the underside of said frame to effect a pivotal movement of said bracket and thereby a movement of said gripping member into engagement with a strap in said guide.

18. In a strap stretching device, a frame having a guide channel through which a strap is adapted to pass endwise, a yoke-shaped bracket embracing said frame and having arms extending upwardly on the outer side of said frame, said frame having side flanges located inside of said arms and provided with apertures, a pin mounted in said arms and loosely engaging said apertures, a gripping wheel mounted on said pin between said flanges and having peripheral teeth adapted to engage said strap in said guide, resilient means engaging said bracket for causing said wheel normally to engage said strap, a lever pivoted on said pin, a pawl carried by said lever and arranged to engage said teeth for rotating said wheel upon reciprocation of said lever, and a detent mounted on said frame and adapted to engage said teeth to hold said wheel between successive working strokes of said lever.

19. In a strap stretching device, a frame having a guide channel and a tip portion provided with a restricted mouth through which a strap is adapted to pass endwise, said mouth having walls adapted to confine said strap along its opposite side edges, and means including a single member located in said channel and having teeth for holding said strap and for effecting endwise movement thereof.

20. In a strap stretching device, a frame having a guide channel and a tip portion provided with a restricted mouth through which a strap is adapted to pass endwise, said mouth having walls adapted to confine said strap along its opposite side edges, a wheel mounted in said channel and having peripheral teeth for engaging said strap, and manually operated means engaging said teeth for rotating said wheel to move said strap through said mouth and said channel.

JAMES N. WOGNUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,313,669 Brooks Aug. 19, 1919 1,517,903 Guenther Dec. 1924 1,905,052 Porter Apr. 25, 1933 2,067,806 Waldorf Jan. 12, 1937 2,349,608 Bramble May 23, 1944 2,368,969 Cleveland Feb. 6, 1945 FOREIGN PATENTS Number Country Date 143,184 Switzerland Oct. 31, 1930 

